Glensound Electronics GS-MPI004, Manual

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PRINCIPLE OF OPERATION
The GS-MPI004 is a portable (belt-pack) quad-band GSM mobile phone unit, with
Mic and Line inputs, and a Line output. The GS-MPI005 is a 1U sub-rack unit,
designed for use in a 19" sub-rack, and contains three functionally separate GSM
mobile phone units, each equivalent to one GS-MPI004 unit.
POWER SUPPLY
The GS-MPI004 can be powered from either an external DC supply (9 – 12V), or
from 4 x AA batteries. The use of Lithium Manganese Dioxide batteries will yield
longer talk times than standard Alkaline batteries. If both an external DC supply
and batteries are connected, the external DC supply will take precedent. Note that
the external DC supply cannot be used to charge the batteries.
A
“LOW BATT” LED is fitted onto the front panel of the GS-MPI004. This LED
will remain off while the battery voltage is above 1.1V per cell. Between 1.1V and
0.92V per cell, the LED will flash with increasing regularity, indicating an
increased urgency to replace the battery. Below 0.92V per cell, the LED will
remain on permanently, indicating that the unit is no longer operational due to low
voltage.
The GS-MPI005, being a sub-rack unit, is powered by a 100 – 240V a.c. mains
supply. The single mains supply is used to power all three GSM mobile phones
inside the unit. Neither the battery box nor the
“LOW BATT” LED are fitted.
ANTENNA
Both the GS-MPI004 and GS-MPI005 use SMA Bulkhead female connectors,
requiring an antenna with an SMA Bulkhead male connector. One antenna is
required per GSM mobile phone unit. The GS-MPI004 contains one mobile
phone, and therefore requires one antenna. The GS-MPI005 contains three mobile
phone units, and therefore requires up to three antennae for full operation.
AUDIO INTERFACE
The GS-MPI004 has separate balanced Mic and Line XLR inputs, which are mixed
together internally. Each mobile phone in the GS-MPI005 has a Line input, but no
Mic input. The input signal is adjusted by an input gain preset on the front panel,
before being passed through a compressor to the GSM interface. Phantom power
is not available on the Mic input of the GS-MPI004. Therefore, only dynamic
microphones can be used.
The audio output from the GSM interface is split between the Line output and the
headphones output. The Line output is adjusted by an output gain preset on the
front panel. The headphones output is mixed with a feed from the input (to provide
sidetone) and adjusted by the “HP VOLUME” knob on the front panel, before
being output on a ¼" Jack socket. On the GS-MPI004, this Jack socket is located
GS-MPI004 / 5 Manual – Issue 2 6